Background: Chronic rhinosinusitis (CRS) is inflammation of the nose and paranasal sinuses with the symptoms duration more than 12 weeks. Many conditions have been linked to its pathogenesis such as bacterial and fungal infection, superantigens and biofilm. Many studies showed the presence of bacterial biofilms in patients with CRS. Bacterial biofilms can facilitate the resistance to antibiotics. Paranasal sinuses (PNS) CT scan is the method of choice for radiological diagnosis of CRS. Lund and Mackay has developed a scoring system based on the CT finding to assess the quantification of inflammatory process in PNS. Some research suggested that patients with bacterial biofilms have higher Lund-Mackay score pre-operatively. Purpose: To determine the role of bacterial biofilms to the severity of CRS according to Lund-Mackay score. Methods: This was a cross-sectional study with 48 CRS patient’s sample. Nasal discharges were taken by swab in middle meatal using sterile cotton buds, followed by identification of bacteria and detection of bacterial biofilms using tube method. Lund-Mackay score was counted from coronal section of PNS CT Scan. Data was analyzed by Fisher’s exact test. Results: Proportion of patients CRS with high Lund-Mackay score was more common in patient with biofilm (46.2%) compared to patients without biofilm (44.4%). Statistically, there was no significant difference of Lund-Mackay score between patient with biofilm and without biofilm (p=1.00). Conclusion: There was no relationship between the bacterial biofilm with the severity of CRS according to Lund-Mackay score.